Field of the Invention
Embodiments of the present invention generally relate to parallel motion estimation in video coding.
Description of the Related Art
Video compression, i.e., video coding, is an essential enabler for digital video products as it enables the storage and transmission of digital video. In general, video compression techniques apply prediction, transformation, quantization, and entropy coding to sequential blocks of pixels in a video sequence to compress, i.e., encode, the video sequence. Video decompression techniques generally perform the inverse of these operations in reverse order to decompress, i.e., decode, a compressed video sequence.
The Joint Collaborative Team on Video Coding (JCT-VC) of ITU-T WP3/16 and ISO/IEC JTC 1/SC 29/WG 11 is currently developing the next-generation video coding standard referred to as High Efficiency Video Coding (HEVC). HEVC is expected to provide around 50% improvement in coding efficiency over the current standard, H.264/AVC, as well as larger resolutions and higher frame rates. Several coding efficiency enhancement tools are proposed in HEVC, among them a merge mode designed to reduce coding overhead by allowing an inter-predicted prediction unit (PU) to inherit motion data, i.e., motion vectors, prediction direction, and reference picture indices, from a position selected from neighboring motion data positions in the same picture and a temporal motion data position derived based on a co-located block of the same size as the PU in a reference picture, referred to as the co-located PU.
A skip mode is also included that can be seen as a coding unit (CU) level merge mode with all zero transform coefficients. Regular motion vector coding for inter-prediction of a PU also considers motion vectors of selected neighboring motion data positions in the same picture and a temporal motion data position derived based on a co-located PU for use as motion vector predictors for the PU. While the currently defined merge mode, skip mode, and regular motion vector prediction do reduce coding overhead, additional improvements are desirable.